Impacts of large herbivorous mammals on bird diversity and abundance in an African savanna

Abstract Large native mammals are declining dramati-cally in abundance across Africa, with strong impacts on both plant and animal community dynamics. However, the net eVects of this large-scale loss in megafauna are poorly understood because responses by several ecologically important groups have not been assessed. We used a large-scale, replicated exclusion experiment in Kenya to investi-gate the impacts of diVerent guilds of native and domestic large herbivores on the diversity and abundance of birds over a 2-year period. The exclusion of large herbivorous native mammals, including zebras (Equus burchelli), giraVes (GiraVa camelopardalis), elephants (Loxodonta africana), and buValos (Syncerus caVer), increased the diversity of birds by 30%. Most of this eVect was attribut-able to the absence of elephants and giraVes; these mega-herbivores reduced both the canopy area of subdominant woody vegetation and the biomass of ground-dwelling arthropods, and both of these factors were good predictors of the diversity of birds. The canopy area of subdominant trees was positively correlated with the diversity of graniv-orous birds. The biomass of ground-dwelling arthropods was positively correlated with the diversity of insectivorous birds. Our results suggest that most native large herbivores are compatible with an abundant and diverse bird fauna, as are cattle if they are at a relatively low stocking rate. Future research should focus on determining the spatial arrange-ments and densities of megaherbivores that will optimize both megaherbivore abundance and bird diversity